The propulsion of walk-behind lawn mowers has historically been operator-powered which required the operator to push the lawn mower around the yard. More recent walk-behind mowers have added self-propelled technology that typically includes a transmission that is powered by the primary engine, wherein the transmission is operatively connected to a pair of opposing wheels of the lawn mower to provide rotational power to those wheels so as to drive the mower. Generally, the self-propelled transmission is a single-speed transmission that is either engaged/on or disengaged/off. These single-speed self-propelled transmissions are typically controlled by an on/off switch or lever positioned on or near the cross-bar of the handle. These switches or levers may include, for example, a fore-aft adjustable lever on one leg of the handle, a rotatable bail that may operate independently or in conjunction with the safety bail, or a trigger-like mechanism, wherein actuation of the switches or levers causes the transmission to become engaged such that the transmission powers the wheels of the lawn mower.
These single-speed self-propelled transmission for a walk-behind mower are often difficult to effectively use by an operator for several reasons. For example, the speed generated by the transmission to the wheels may cause the lawn mower to travel at a speed that can be too fast or too slow for the operator. As such, if the propelled speed is too slow, the operator ends up providing the pushing force. On the other hand, if the propelled speed is too fast, the operator ends up being dragged along by the lawn mower. In either situation, transmission often cannot be optimized for each individual operator. Alternatively, when an operator approaches an object such as a tree, house, sidewalk, posts, or the like, the operator often desires to slow down to make turns or navigate the lawn mower around these obstacles, but the self-propelled transmission being engaged causes the lawn mower to proceed at the same speed which can make avoiding obstacles more difficult.
Therefore, a need exists for a multiple speed control mechanism for adjusting the speed of the self-propelled transmission between a plurality of different speeds. A need also exists for a convenient and ergonomic speed control assembly that allows independent actuation of the self-propelled transmission by either hand of the operator while also adjusting the speed level.